OPERATION SPECIFICATION

FOR

TESCAN MIRA3 ELECTRON BEAM LITHOGRAPHY

Rev. Date Prepared by

01 03/05/2018 Manouchehr Teimouri

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1 SCOPE

1.1 The purpose of this document is to describe requirements and basic

operating instructions for the TESCAN MIRA 3, E-Beam Lithography tool.

This tool is intended for nano-patterning by electron beam.

2 SAFETY

2.1 Must be trained and signed off to use this equipment.

2.2 Record the tool malfunction, breakage, etc. in the log-sheet and send an

email to staff. Never try to fix anything by yourself.

3 APPLICABLE DOCUMENTS, MATERIALS AND REQUIREMENTS

3.1 For more information about the detailed operation of this tool refer to the

TESCAN factory manual – “DRAWBeam for Electron Beam Lithography” File

name: TESCAN MIRA 3 Manual.pdf.

4 OPERATION

4.1 Loading the sample

4.1.1 Log into Mira-TC software by clicking on MIRA3-TESCAN icon and entering user name

and password.

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4.1.2 Vent the chamber by clicking on the VENT button on the Vacuum Panel and wait to

reach “Venting finished” status. (Note: make sure the stage is at home position (X=0;

Y=0; Z=40; Rot & Tilt = 0) before you vent the chamber. If not, click on Home button in

stage control panel).

4.1.3 Open the chamber gently and load the sample onto sample holder. User must have

clean gloves on while loading and unloading the sample.

4.1.4 Gently close the chamber and hold the chamber’s door.

4.1.5 Pump the chamber by clicking on the PUMP button on the Vacuum Panel and wait to

reach “Vacuum ready” status.

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4.2 Turning on the electron beam

4.2.1 Move the stage above gold standard position

4.2.2 Open the “Beam Blanker” panel in the main SEM menu and select “Enable beam on

acquisition”.

4.2.3 Select SE detector in the SEM Detectors & Mixer panel. Make sure the BSE detector is

retracted.

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4.2.4 Set the exposure parameters including acceleration voltage (HV; 30 kV is recommended)

and Beam Index (BI; less than or equal to 5 is recommended) in Info Panel. (Note: for

large patterns where both dimensions are in the range of few tens of microns and

resolution is not as critical, use BI 8-10 to reduce the exposure time (higher BI is

equivalent to higher beam current)).

4.2.5 Turn the electron beam on by clicking on the BEAM ON button on the Electron Beam

panel.

4.2.6 Perform focus on gold standard at 50kx by turning WD knob on Control Panel. Once the

gold standard is focused, gradually decrease WD&Z in stage control panel (WD&Z = 15,

10, and then 6.0) and re-perform focus until gold standard is focused at WD 6.0.

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4.3 Electron Column Alignment

4.3.1 Perform fine focusing at magnifications ≥200kx.

4.3.2 Perform gun centering by automatic procedure. Click on AUTO GUN CENTERING on the

Electron Beam panel.

4.3.3 Perform Column Centering (Centering the aperture) manually. Click on icon on

the toolbar and use control panel knobs ( for X and for Y) or the trackball to

center the aperture.

4.3.4 Correct Astigmatism (Correcting non-circularity in electron beam). Click on icon

on the toolbar and use control panel knobs or the trackball.

4.3.5 Re-Perform focusing.

4.4 Exposure

4.4.1 Open the DrawBeam panel in the main Tools menu.

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4.4.2 Create a new project/open a saved project/ import from GDSII format by clicking on the

/ / icon.

4.4.3 Click on the icon in the DrawBeam panel to open the DrawBeam Process panel.

Enter the suitable Dose(s) and Spacing by double click on Dose window. (Note: keep the

spacing at minimum possible value;

(1) Exp pitch should be ≥ 4×DAC resolution (DAC resolution depends on view field)

(2) Exp pitch = spot size × spacing

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4.4.4 Move the stage to the faraday cup. Magnify to 50kx (the entire screen should be black;

i.e. all the electrons should be collected by faraday cup). Measure the beam current by

clicking on icon in the DrawBeam Process panel. The correct value of the beam

current will be automatically inserted in the panel.

4.4.5 Move the stage to the edge of the sample and find the scratch you made on sample

after spin coating. Click on Define UV and then Align sample to align sample with x and y

directions.

4.4.6 Go to the tip of the scratch. Take caution not to expose the sample. Find a tiny particle

and try to bring the particle on focus without changing WD. In order to do that you

need to change Z. Keep changing Z using buttons until you see a clear image

of the particle.

4.4.7 Open the Analysis & Measurement panel in the main Tools menu (steps 4.4.7-4.4.9 are

optional if step 4.4.6 is performed properly).

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4.4.8 Click on the New Point/line button and place the point (Magnification should be 400kx).

Start and stop the burning by clicking on the icon. The burning time is 10-20

seconds.

4.4.9 Perform final focusing and astigmatism correction on the spot to achieve an ideal

circular spot. Repeat burning and focusing, if necessary.

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4.4.10 Blank the beam by clicking on the Single button on the Info Panel.

4.4.11 Move the stage to exposure location by entering new X and/or Y coordinates.

4.4.12 Start the exposure by clicking on button in the DrawBeam Process panel. Move the

stage and start another exposure, if needed.

4.4.13 After exposure is finished, turn the beam off by clicking on the BEAM ON button on the

Electron Beam panel.

4.5 Unloading the sample

4.5.1 Move the stage to home location by clicking on home button in Stage Control Panel.

4.5.2 Vent the chamber by clicking on the VENT button on the Vacuum Panel and wait to

reach “Venting finished” status.

4.5.3 Open the chamber gently and unload the sample.

4.5.4 Gently close the chamber and hold the chamber’s door.

4.5.5 Pump the chamber by clicking on the PUMP button on the Vacuum Panel and wait to

reach “Vacuum ready” status.

4.5.6 Log off the software. Click on the log off in the main tools menu. You will be asked two

question: 1) do you really wish to log off: Yes 2) Go to the STANDBY mode: No

4.5.7 Fill out the log-sheet.

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Appendix A:

Some Examples for writing circles, lines, rings, and texts

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Appendix B:

PMMA Spin Coating and Developing

PMMA is purchased from Micro Chem

Spin Coating:

Step 1: 500 rpm, 5 seconds, 100 rpm/s

Step 2: 3000 rpm, 45 seconds, 500 rpm/s

Soft baking: 185 C for 90 seconds

Thickness: 950 PMMA A2: ~ 80 nm ; 950 PMMA A4: ~ 240 nm

Developer: 1:3 MIBK:IPA (MIBK: 4-Methyl-2-pentanone; purchased from Sigma Aldrich)

Develop time: gently shaking for 60 seconds

Wash thoroughly with DI Water after develop

Dry with N2.